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commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world.
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Every new command is wrapped in a tweet and posted
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This will kill a specific process you don't know the PID of, when pidof and pgrep are not available, for example on OS X. var1 is created so that the whitespace can be trimmed before passing off to kill.

This function is used to sort selected lines of a text file to the end of that file. Especially useful in cases where human intervention is necessary to sort out parts of a file. Let's say that you have a text file which contains the words

rough

slimy

red

fluff

dough

For whatever reason, you want to sort all words rhyming with 'tough' to the bottom of the file, and all words denoting colors to the top, while keeping the order of the rest of the file intact.

'$EDITOR' will open, showing all of the lines in the given file, numbered with '0' padding. Adding a '~' to the beginning of the line will cause the line to sort to the end of the file, adding '!' will cause it to sort to the beginning.

If you have multiple displays or monitors the DISPLAY environment variable will tell X where to send the output. This is very handy for setting up a mediacenter at home. You can plugin the computer to the TV and then ssh to the computer and set the DISPLAY as above, then run your program and it will show up on the TV.

Very useful in shell scripts because you can run a task nicely in the background using job-control and output progress until it completes.

Here's an example of how I use it in backup scripts to run gpg in the background to encrypt an archive file (which I create in this same way). $! is the process ID of the last run command, which is saved here as the variable PI, then sleeper is called with the process id of the gpg task (PI), and sleeper is also specified to output : instead of the default . every 3 seconds instead of the default 1. So a shorter version would be sleeper $!;

The wait is also used here, though it may not be needed on your system.